Hi All,

   I'm playing catch-up from a week's absence.

<< Thanks again for the tips.  What if I filled the core with water prior to
>  welding?  Maybe I could change the water periodically as it heats up?  Would
>  the water vapor be a problem with TIG welding?  At least I'd know if I
>  reached the kit stage :-)
>
>
> Well, it would work fine so long as the water is not very close to the area
> to be welded. Any hint of steam blows away the curtain gas (argon) and ruins
> the weld.
> I have never tried that idea. So between welds, the area must be obsoletely
> dry.
> With a wet rag, you can be cooling the brazed joints while having a dry weld
> area.
> It sounds like a big deal, but once you try it, it goes real fast. You nail
> the power, weld for a few seconds, maybe 3/4" long bead, and stop. Let it cool
> down, and go again. It is just too easy.
>

   There is a heat conductive paste available, at welding shops, and gunsmith supply houses like Brownell's, that is
made especially for this task.  It will let you weld longer than the wet rags will allow.

   Most emphatically, I would not weld anything "pressure critical" with water in the tubes.  To protect the joints between tube and fin, the paste can even be worked into the fins, and then washed out with hot water later (some will run out from the heat of welding).

Regards,
Dale R.